It is in the field of hepatology that enzyme assays are performed most frequently for diagnostic purposes. Their interpretation requires knowledge of many factors that influence the serum level of the particular enzymes assayed. Therefore, these factors are discussed briefly in relation to liver disease before considering important developments such as the value of estimating D-glutamyltransfer...

Despite the broad use of enzymes in electroanalytical biosensors, the influence of enzyme kinetics on the function of prototype sensors is often overlooked or neglected. In the present study, we employ amperometry as an alternative or complementary method to study the kinetics of tyrosinase, whose catalytic activity results in o-quinone products. We further compare our results for four monophen...

During 1969, discussions between the Standards Subcommittee of the Laboratory Equipment and Methods Advisory Group of the Department of Health and Social Security and representatives of professional societies concerned with the assay of enzymes for diagnostic purposes led to the establishment of a working party to consider the current state of accuracy and reliability of diagnostic enzymology a...

A kinetic enzymological assay for methotrexate in serum is described; the results are available after 1.5 hours. The lower limit of sensivity is 50 nmol/1; the day-to-day variation coefficients compare favourably with other procedures (about 7% in the 200-600 nmol/1 range). The method uses purified dihydrofolic acid reductase from bovine liver. The problem of its instability in the assay is ci...

Assay cocktail modification such as addition of effector can cause inadvertent changes in the concentration of other metalligand and free species. In some cases, e.g. in the assay for phosphoenolpyruvate carboxylase under a limiting-substrate condition, unintentional changes in substrate concentration are significant and confound an interpretation based solely on the total concentration of each...